How cloud mapping can tell us more about our planet

Jamie Stevenson
London 51° 30' 23.112" N, -0° 7' 37.956" E" E

Cloud cover impacts more than your ability to top up a tan – it can provide vital information about ecological issues, and offer insight into the world we live in. In a bid to uncover this, researchers have created a detailed, visually striking cloud map database.

We spoke with Adam Wilson, one of the creators of the project, about the database and what it can tell us about our planet.

adam_300“We were interested in developing better environmental data to understand the global distribution of biodiversity. Many aspects we were focusing on – temperature, precipitation – are already available to view on a global level.”

“However, we knew that these weren’t the only things we needed to look at, so started looking at additional factors that might be important. This lead us to think about clouds and cloud cover.”

 

Cloudy with a chance of mapping

Adam, now a professor at the University at Buffalo, New York, worked on the cloud mapping project as post-doctoral research at Yale University for around two years. He tells us more about what he and his colleague, Walter Jetz, wanted to achieve with the project:

“Most of the prior work on cloud cover either has high spatial resolution or global coverage, but not both.  So you could pick one mountain range, or one area to cover, but not see the bigger picture. Or you could see the bigger picture, but not the details.  We wanted to achieve a global map of cloud dynamics, with really high spatial resolution.”

By being able to map global cloud cover at 1km spatial resolution, Adam and Walter have created a database of detailed, striking maps that can tell us more about life on Earth. Adam adds, “By processing and summarising that climate data, we can offer real insight into fine-grain global cloud dynamics and the impacts on ecological processes.”

Creating the maps

The data for the project was gathered by two NASA satellites equipped with MODIS (Moderate Resolution Imaging Spectroradiometer), which, Adam tells us, is a special kind of camera that captures imagery across the electromagnetic spectrum (both visible and infrared).

cloud_body

Then, Adam and Walter created the necessary datasets using twice-daily observations from the last 15-years of MODIS images, all at 1km resolution.

Adam adds, “As you can imagine, this was quite time-consuming. Our job then was to process the full dataset down to summary layers that would actually be useful for analysis and discovery. Once this was accomplished, we had to correct for some artefacts in the data and validate with ground observations of cloud cover.

“The way the satellites orbit means that they can’t offer the highest resolution image at all times, so there was a bit of correction to account for. Once we had the summary images, the next question was: are these images useful for the type of questions we want to pose?”

Mapping life

Indeed, the cloud database can answer more serious questions than, say: where shall I go on holiday? Adam explains, “We were especially interested in the spatial distribution of species on earth. We often rely on environmental data to identify species habitat, for example, some trees can’t survive frost, so if you can identify which regions on earth are frost-free you can infer where these trees may be able to survive.”

“If you include additional environmental variables to this model, you can continue to refine species habitats. So we were using cloud data in addition to existing data to discover more about the distribution of species on earth. This additional data also helped us to refine our maps of the spatial distribution of several species.”journal.pbio.1002415.g001

These findings, Adam adds, were often surprising: “When we first produced and looked at the global image you could really see the biomes of earth, clearly delineated by the different colours on this map.”

“We were able to see how variable the climate regions on Earth are – the Mediterranean, Southwestern Australia or California – and really observe these regions’ unique cloud cover climatology. For example, the monsoonal regions popped out in these strong, blue-ish colours indicating a particular seasonality of cloud cover.”

Adam states that, while this was the goal, it was still a surprise to see it so vividly produced. He adds, “We expected to see this, but at the same time, the 1km resolution revealed stark delineations between biomes.  We can identify the cloud climatology for any place on earth and see how it fits in with other climate patterns around the world.”

More to discover

With the maps already providing useful information around climatology and ecological issues, Adam still feels it has more to give:

“We’re entering a new era in our ability to observe Earth from space and see how it has changed through time.  Over the past 15 or so years much of the research using satellite data has focused on producing static maps. Now that we have several decades of these observations, we can monitor changes over time - how forests change from month-to-month or year-to-year, for example.

“Observing ecological processes on the ground is, in many ways, the best approach, but it’s also very expensive. While I don’t think we’ll be able to replace that, the ability to look anywhere on Earth, going back the last few decades, and observe change is very powerful. It’s an incredibly rich archive which we can look to, and helps us to pose new questions.”

“Honestly, we’re really just getting started here.”

Have you seen the cloud maps? Let us know your thoughts in the comments below.

Topics: Cartography, Features, Editor's Picks, Science of Maps

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